DevotedSkeptic writes: "The protoplanet Vesta, a large space rock in the solar system's asteroid belt, is covered with a surprising amount of hydrogen, and bits of Vesta may have rained down on Earth in the form of meteorites, NASA's Dawn probe has revealed.

Dawn spent more than a year orbiting Vesta, a behemoth 330-mile-wide asteroid that circles the sun between the orbits of Mars and Jupiter. Earlier this month, on Sept. 5, Dawn took its leave of Vesta to begin trekking to the even-larger space rock Ceres, which is categorized as a dwarf planet.

Meanwhile, though, scientists are still poring over the treasure trove of data on Vesta gathered by the probe, and two new studies are reported on Sept. 20 in the journal Science. In one, researchers report the findings of Dawn's Gamma Ray and Neutron Detector (GRAND), which mapped the elemental composition of Vesta's surface."